External Mail clients can't send after upgrade

First off, I think you guys should run a report of all the users that post the most on this forum. I bet i'm up there.

LOL

But anyways, to my problem... I just upgraded from 7.10 to 8.04 ubuntu and now I can't send mail from my external clients. I have them using authentication but still no luck. Is there anything that I need to enable or anything in one of the config files that would of been re-written?